JPH03242877A - Dubbing system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dubbing system, and particularly to a system for dubbing an information code string in which the amount of information is compressed by high-efficiency encoding and an error correction code is added.

[Conventional technology]

In recent years, digital VTRs and digital audio tape recorders (DATs) that do not deteriorate during dubbing have attracted attention.

FIG. 4 shows a general configuration of a system for dubbing using two digital VTRs. In the figure, S is the slave side (
Recording side) VTR, M is a master side (playback side) VTR. In addition, in the figure, for ease of explanation, the master side V
For TR (M), playback system, slave side VTR (S)
Only the recording system is shown.

In the master side VTR (M), the recording signal of the magnetic tape T1 is converted into an electric signal by the magnetic head 26,
The signal is amplified by a reproduction amplifier 28. Note that recording was performed using a normal recording/playback device.

The output of the reproduction amplifier 28 is demodulated by a digital demodulation circuit (not shown) and then applied to the ECC decoder 30.

The ECC decoder 30 uses an error correction code added to the recorded information code string to correct code errors during reproduction. The expansion circuit 32 performs processing opposite to the encoding process, that is, band expansion and decoding, to the band compression encoded information code output from the ECC decoder 30, and the correction circuit 3
Supply to 4. The circuit 34 is a circuit that corrects the uncorrectable information code by processing such as interpolation using the correlation of the information when the reproduced code error exceeds the correction ability of the ECC decoder 30. The D/A converter 36 is a correction circuit 34
The output is converted into an analog signal and output to the output terminal 38. In addition, the output of the modification circuit 34 is output from the dubbing output terminal 3.
5.

On the other hand, in the slave side VTR (S), the input terminal 10
The video signal input to the digital signal generator 12 is digitized by the A/D converter 12 and supplied to the band compression encoding circuit 16 via the N side of the changeover switch 14 . The FCC encoder 18 is
An error correction code, so-called parity, is added to the signal band compression encoded by the band compression encoding circuit 16 to correct code errors that occur during reproduction. The output of the FCC encoder 18 is modulated by a digital modulation circuit (not shown), then amplified by a recording amplifier 20, and then sent to a magnetic head 22.
The information is magnetically recorded on the magnetic tape T2.

During dubbing, the output of the modification circuit 34 of the master side VTR (M) is transmitted to the slave side VTR (M) via the terminal 35.
(S) is input to the dubbing input terminal 37. This is to prevent dubbing of an erroneous code when an uncorrectable code error occurs in the reproduced information code. In this way, the modified information code string is input to the terminal 37, the modified code is applied to the compression encoding circuit 16, and after compression encoding processing is performed again, the magnetic tape T
2 is magnetically recorded.

In the case of a digital VTR, unlike an analog VTR, it is not affected by distortion in the electromagnetic conversion system, and therefore, the only deterioration in image quality is due to band compression and error correction when errors occur frequently. Also, regarding dubbing, it is said to be more advantageous than analog VTRs in that there is no accumulation of deterioration due to distortion in the electromagnetic conversion system.

[Problem to be solved by the invention]

However, in the above conventional example, when dubbing, the switch 14 is connected to the D side and the modified data output from the modifying circuit 34 is compressed again and magnetically recorded. There is a problem that image quality deteriorates.

Therefore, an object of the present invention is to provide a dubbing system that solves these problems.

[Means to solve the problem]

For this purpose, in the present invention, an information code string whose information amount has been compressed by compression encoding and an error correction code has been added is reproduced from a recording medium by a reproduction side device, and In a dubbing system in which a dubbing device records on another recording medium, the re-master side device includes an error correction means for correcting errors in a reproduced information code string, and an error correction means for correcting errors in the reproduced information code string; Apply decoding corresponding to encoding,
It has a decoding means for expanding the amount of information, and an error correction means for correcting information codes that cannot be corrected by the error correction means in the information code string passed through the decoding means by using the correlation of the information. However, the uncorrectable information code is supplied to the recording side device via the error correction means, and other information codes are supplied to the recording side device without going through the error correction means.

[Effect]

In the above-mentioned system, only the codes whose errors could not be corrected during reproduction are corrected and recompressed, and the codes for which error correction is possible and the codes in which no errors have occurred are dubbed as they are compressed. Unnecessary expansion/compression processing is no longer performed, and image quality deterioration can be minimized.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a dubbing system according to an embodiment of the present invention, in which the same components as in FIG. 4 are designated by the same reference numerals. Also, in Figure 1, only the playback system is shown for the master side VTR (M), and the slave side VT
R(S) indicates only the recording system.

The ECC encoder 30 supplies the error position storage circuit 40 with a flag indicating whether or not the code is an error-correctable code.

The circuit 40 stores the position on each data frame of the code in which the uncorrectable code error has occurred, and stores the position on each data frame of the code in which the uncorrectable code error has occurred, and stores it at the timing when the code in which the uncorrectable code error has occurred, that is, the corrected code, is outputted from the correction circuit 34. , and supplies flag data indicating this to the terminal 41. 42 is a delay circuit for a predetermined delay time, which will be described later, and outputs a delayed compressed information code string to a terminal 45.

44 is a switch that selectively applies the code string delayed by the delay circuit 42 and input via the terminal 47 and the code string output from the compression encoding circuit 16 to the ECC encoder 18; It is controlled by the flag data input from the error position storage circuit 40 mentioned above.

Since the predetermined normal recording/reproducing operation is the same as that shown in FIG. 1, the following description will focus on the dubbing operation. FIG. 2 is a diagram schematically showing the code strings of each part. In Figure 2,
D, (i=1 to n) is data, Pl is parity, ED,
is data in which errors remain even after error correction by the ECC encoder 30, and F is an error flag indicating whether each code after error correction is valid or not. The error flag F is "1" if a code error remains in the corrected code (if it cannot be corrected), and "1" if no code error remains (if it is correctable or if there is no code error). O"'. Second
In the figure, it is assumed that a code whose error cannot be corrected remains in the data D2, and the other codes are completely corrected by the ECC encoder 30 even if there is a code error.

Figure 2 (1) shows the ECC encoder 3 during the first dubbing.
The input code string to 0 is shown. That is, a predetermined number of symbols of parity P is added to a code of a predetermined number of symbols (i=1 to n).

For example, in the Reed-Solomon (36,32) system, 4 symbols of parity are added to a 32 symbol code string, and code errors of 2 symbols can be corrected.

FIG. 2(2) schematically shows a code string 48 output from the ECC encoder 30. The code error of code D1 is converted to parity P.
1, and at the same time as the next code D2 is input to the ECC encoder 30 (strictly speaking, error correction decoding time is required, but it is not essential in this embodiment, so it is ignored), the corrected code D1 is input to the ECC encoder 30. An error flag F indicating the presence or absence of a subsequent code error is output. Since no code error remains for the code D1, the error flag F1 is "0" in this case.

For code D2, the ECC encoder 30 cannot correct all code errors, and the code E including code errors is
D2 is output, and the error flag F2 is "1". D
8 to D, even if there is a code error, it is completely corrected, and the error flags F3 to Fn are "0".

FIG. 2 (3) shows the code string 5 output from the compression encoding circuit 16.
4, the output 48 of the ECC encoder 30 is a signal that has been expanded, modified, and recompressed by the expansion circuit 32) modification circuit 34 and compression encoding circuit 16. Modification circuit 3
In order to indicate the modification by 4, the subscript a of data D2 is added.

That is, code ED2 with a code error has changed to modified data D2m. At this time, the output 54 of the compression encoding circuit 16 is
) There is a delay of time τ corresponding to the processing time in the modification circuit 34 and the compression encoding circuit 16, and the delay time of the delay circuit 42 is also set to this time τ. FIG. 2(4) shows the output signal 58 of the delay circuit 42.

The error position storage circuit 40 stores an error flag F (in this embodiment, F2) set to "1", and the corresponding code (D2 in this embodiment) is stored at the terminal 35.45. The switch 44 is switched to the b contact side at the timing of the output from the . That is, the switch 44 is
For codes whose errors could not be corrected even by the ECC encoder 30, connect them to the b contact side, select the code corrected by the correction circuit 34 and recompressed by the compression encoding circuit 16, and send the code to the output stage of the ECC encoder 30. For codes with no code errors, by connecting them to the a-contact side, the time-adjusted compressed information code with no errors is selected by the delay circuit 42. FIG. 2(5) shows the code string selected in this way (specifically, the output of the ECC encoder 18). The ECC encoder 18 converts the modified code D2m into a parity P2.m that is different from the original parity P2. Add. Naturally, the same parities P, P3 to P are added to the other codes D + and D s to D□.

Note that the code string 58 (FIG. 2 (4)) and the code string 56 (second
The time difference T with FIG. 5 (5) corresponds to the processing time of the ECC encoder 18.

2 As described above, in this embodiment, if there is no uncorrectable code error in the code to be dubbed, the band-compressed code is dubbed as is, and only when an error remains,
Extend, modify, and recompress before dubbing. Thereby, image quality deterioration due to repeated band compression can be minimized.

FIG. 3 is a block diagram showing the configuration of a dubbing system as another embodiment of the present invention, and parts in the figure that perform the same functions as those in FIG. 1 are given the same numbers. As shown in the figure, the system of this embodiment is controlled by a compression encoding circuit 16' that compresses and encodes the output of the correction circuit 34 in the master side VTR (M) and flag data output from the error position storage circuit 40. A switch 44' is provided and the first
In the system shown in the figure, the dubbing code string obtained from the switch 44 during dubbing is obtained by the switch 44'.

Therefore, the code string output from this switch 44' is transmitted to the input terminal 5 of the slave side VTR (S) via the output terminal 51.
3, and during dubbing, the switch 19 records the input code string from this input terminal 53 instead of the code string output from the compression circuit 16. This provides the same effect as the system of FIG. 1. Furthermore, in the system of this embodiment, compared to the system shown in FIG.
This has the advantage that the number of connection lines between the R (M) and the slave side VTR (S) is reduced.

Although the above description takes a magnetic tape as an example of a recording medium, it goes without saying that the present invention can also be applied to recording and reproducing devices for various recording media such as optical disks, magneto-optical disks, and solid-state memories.

〔Effect of the invention〕

As can be easily understood from the above description, according to the dubbing system of the present invention, dubbing can be performed with less deterioration of information, and the characteristics of the digital recording/reproducing apparatus can be utilized to the maximum.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a dubbing system according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the code strings of each part of FIG. 1, and FIG. Block Diagram Showing Configuration of Dubbing System FIG. 4 is a block diagram showing an example of the configuration of a conventional dubbing system. In the figure, 16 is a band compression encoding circuit, 18 is an ECC encoder, 20 is a recording amplifier, 22 is a magnetic head, 28 is a reproduction amplifier, 30 is an ECC encoder, 32 is an expansion circuit, 3
4 is a correction circuit, 40 is an error position storage circuit, 42 is a delay circuit, 35, 45, 51 are output terminals, 43, 47.
53 are input terminals, M is a master side VTR, S is a slave side VTR, and Tl and T2 are magnetic tapes.

Claims (3)

[Claims] (1) Dubbing in which an information code string whose amount of information has been compressed by compression encoding and an error correction code has been added is reproduced from a recording medium by a reproduction device, and recorded onto another recording medium by a recording device. The reproduction side device includes an error correction means for correcting errors in the reproduced information code string, and decoding the information code string via the error correction means in accordance with the compression encoding, and reads the information. and an error correction means for correcting information codes that cannot be corrected by the error correction means in the information code string passed through the decoding means, using the correlation of the information, Dubbing characterized in that the uncorrectable information code is supplied to the recording side device via the error correction means, and other information codes are supplied to the recording side device without going through the error correction means. system. (2) In the system according to claim (1), the reproduction side device has a first output terminal for outputting the information code on the input side of the decoding means, and an information code on the output side of the modification means. , and the recording side device includes first and second input terminals for inputting information codes outputted from the first and second output terminals. dubbing system. (3) In the system according to claim (1), the reproduction side device includes a compression encoding means for applying the compression encoding to the information code output from the modification means, and an input side of the decoding means. an output terminal for selectively outputting the information code and the information code output from the compression encoding means, and the recording side device includes an input terminal for inputting the information code output from the output terminal. Features a dubbing system.